The present invention relates to a mass spectrometer and a mass spectrometry method utilized in that mass spectrometer.
In mass spectrometry utilizing an ion trap by the method disclosed in U.S. Pat. No. 5,572,022, the total counts of ions extracted from the ion trap is first measured, and based on that information the total counts of ions introduced to the ion trap is regulated and mass spectrometry performed under conditions where there is minimal effect from space charge.
U.S. Pat. No. 6,884,996 discloses a method for performing high efficiency mass spectrometry or mass spectrometry analysis by compensating for the shift in resonant frequency occurring due to space charge at the resonant frequency utilized for isolating the precursor ion and dissociation during tandem mass spectrometry analysis. In this method, the quantity of trapped ions is estimated from the time that the ions were introduced into the ion trap, and the shift in resonant frequency due to the space charge then calculated from that ion counts.
United States Patent Publication No. 2006/0289743 discloses a method for compensating for the mass shift due to space charge by finding the total ion counts on the mass spectrum.